1. Field of the Invention
The present invention relates generally to semiconductor fabrication methods and apparatus, and more particularly to a method and apparatus for reducing particulates deposited on semiconductor substrates during fabrication.
2. Description of the Prior Art
Semiconductor devices are commonly manufactured by sequentially performing a number of process steps to an exposed surface of a semiconductor substrate. The process steps typically include implanting dopant ions in the semiconductor material immediately below the exposed surface, depositing films on the exposed surface by processes such as chemical vapor deposition and sputtering, and etching selected portions of the substrate and deposited films. Such processes generally are performed inside air-tight chambers operating at interior gas pressures below atmospheric pressure.
A continuing problem in developing and using semiconductor fabrication processes is to prevent spurious particulates from being deposited on the semiconductor devices. This problem is especially difficult to address because it is difficult to detect the presence of particulates only a few microns in diameter, and even more difficult to determine the source or cause of the particulates. Of course, there are many different sources contributing to particulates in semiconductor fabrication. As each source is discovered, a solution can be developed to reduce or eliminate the generation of particulates by that source, thereby contributing to an overall reduction in the contamination of semiconductor devices by spurious particulates.